Surgical tissue protection sheath

ABSTRACT

A surgical sheath adapted for use in the nasal cavity has an elongated hollow body made of a braided material having interstitial spaces with a dimension of 0.25 mm to 1.50 mm. The interstitial spaces filled with a filling material, such as silicone. The sheath has a low profile configuration during placement into the naris, and may be stretched into an expanded configuration. In methods of placing the sheath in the naris, the sheath is folded and then pulled into the naris using a surgical tool.

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/680,947 filed Aug. 18, 2017 and now pending, which is acontinuation-in-part of U.S. patent application Ser. No. 15/340,718filed Nov. 1, 2016, now U.S. Pat. No. 9,494,621, which is a continuationof U.S. patent application Ser. No. 14/626,184 filed Feb. 19, 2015 andnow abandoned, which is a continuation of U.S. patent application Ser.No. 13/798,990 filed Mar. 13, 2013, now U.S. Pat. No. 8,986,201. U.S.patent application Ser. No. 15/680,947 claims priority to U.S.Provisional Patent Application No. 62/396,746 filed Sep. 19, 2016 andU.S. Provisional Patent Application No. 62/377,400 filed Aug. 19, 2016.Each of the applications listed above is incorporated herein byreference.

BACKGROUND

Endoscopic surgery within the head is a common procedure in neurologicalsurgery and otolaryngology. It avoids large cranial incisions and canreduce the need brain retraction and prolonged wound healing. Endoscopicsurgery within the head also provides improved illumination andvisualization of the target tissues because the camera of the endoscopeis brought directly to the surgical site.

During this type of surgery, there may be local trauma to the tissues inthe surgical pathway, resulting from pressure or abrasion caused by thesurgical tools. Generally these tissues are the nasal mucosa,turbinates, nasal septum, and sphenoid/frontal/maxillary sinus. Whentransorbital approaches are used, orbital and periorbital tissue aresubject to local trauma. Surgical pathway trauma can add to the traumaof the procedure and prolong the patient's recovery time. Liquids in thesurgical pathway, such as mucous, blood, and soiled irrigation fluid,tend to obscure the view of the endoscope. This leads to the constantneed for irrigation and suction of the obstructing liquids. In somecases the endoscope may also have to be removed, cleaned and replacedmultiple times during a single procedure. This disadvantage tends toincrease the complexity and time requirements of the operation. Inaddition, with each movement of a surgical tool into or out of thesurgical pathway, the surrounding tissues are put at risk of additionaltrauma. Improved devices and methods are therefore needed.

SUMMARY OF THE INVENTION

An access sheath is provided to protect the nasal passageway duringendoscopic trans nasal or intra ocular surgery. The access sheathprotects the entrance of the naris and sinus from the placement andmanipulation of surgical tools both during the initial placement andduring manipulation and exchange of surgical tools. The access sheathmay provide a guide port to help direct surgical tools into position. Insome designs the access sheath may splint the sinus open, to help openand provide access past the turbinate. The access sheath may also helpto keep surgical tools and especially an endoscope freer from obscuringmatter and secretions

The access sheath may be flexible for placement in a folded or rolled upconfiguration, have a hoop or expansion capability to fill and splintthe passage, be partially or totally fluid tight to reduce ingress ofsecretions, and be lubricious for the unobstructed motion of finesurgical tools during delicate micro surgery.

U.S. Pat. No. 8,986,201 B2 discloses an access sheath, which may be madeof elastomer, and has many of the performance features described above.However, elastomer has an inherent draw back. Flexible elastomers areinherently tacky and hence create sliding friction on surgical tools. Insome designs this has required additives or a coating on the surface ofaccess sheath to reduce friction. Still generally additives and coatingscannot always provide the surgeon with the feel of a surgical toolsliding against a wet mucus layer.

A nasal access sheath made of a hard plastic material is manufactured ina way to make it flexible, in one embodiment, by using a braided tube. Abraid can be made from multiple fibers of plastic monofilament.Monofilaments can be made of rigid and tough plastic such as PET(Polyethylene terephthalate) or Nylon. Monofilaments can even be madefrom stainless steel. The fibers remain flexible because they have asmall diameter, such as 0.08 mm to 0.5 mm. The fibers may have a roundcross section, a relatively flat cross section, or elliptical crosssection. A plurality of fibers can be braided into a braided tube. Asone example, 64 fibers are counter wound in a two over and two underbraid. The angle (pics or pitch) of the braided fibers can select thecircular profile of the resulting braided tube or sleeve. A braided tubeadditionally is flexible due to the loose association of the braidedfibers and their ability to slide relative to each other but stillmaintain the intended braided pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, the same reference number indicates the same element ineach of the views.

FIG. 1 shows a braided tube.

FIG. 2 shows a braided tube expanded and loaded over a cylindricalmandrel.

FIG. 3A shows a forming mandrel shaped with a geometry for use in thehuman sinus.

FIG. 3B shows a braided tube expanded and loaded over the formingmandrel of FIG. 3A.

FIG. 4 shows a braided tube that has been heat formed and the mandrel ofFIG. 3A removed.

FIG. 5 shows a heat formed braided tube that has been coated with anelastomer.

FIG. 6 shows a heat formed braided tube with the braid inverted to forma dual layer, and with the distal end folded back on itself to provide arounded tip.

FIG. 7A shows a braided tube created by a single layer of braid formedwith a continuation distally of unformed braid. The formed portion wasthen dipped in a coating of elastomer.

FIG. 7B show the structure of 7A, where the uncoated distal extension ofbraid has been inverted back through the formed and coated section.

FIG. 7C shows the structure of FIG. 7A where the uncoated distalextension of braid was then inverted resulting in a braided tube havinga rounded distal end and an un-coated inner surface and a coated outersection.

FIG. 8A shows the distal end or edge of a single layer braided tube.

FIG. 8B shows the distal end of a two layer braided tube with aninverted distal end.

FIG. 9A shows the coated braided tube of FIG. 7C or 8B with two surgicaltools placed in parallel.

FIG. 9B shows the coated braided tube with two surgical tools at anacute angle and the flexible response of the neck of the structure.

FIG. 10A shows the coated braided tube next two an introduction toolthat has a longitudinal release slot.

FIG. 10B shows the coated braided tube loaded into the introduction toolof FIG. 10A.

FIG. 10C shows the loaded introduction tool being inserted into thenose.

FIG. 10D shows the introduction tool fully inserted into the nose.

FIG. 10E shows the coated braided tube being mostly released out of thelongitudinal release slot of the introduction tool.

FIG. 10F shows the coated braided tube fully released out of thelongitudinal release slot.

FIG. 11A shows the access sheath and a plunger deployment tool.

FIG. 11B shows the access sheath loaded in the plunger deployment tool.

FIG. 11C shows the access sheath expelled distally from the plungerdeployment tool.

FIG. 12A shows a beam and groove scissor-like delivery tool in an openposition.

FIG. 12B shows the delivery tool of FIG. 12A in a closed position.

FIG. 12C is a top view of the access sheath of FIG. 5, 8A or 9 loadedonto the delivery tool.

FIG. 12D is a side view of the access sheath and delivery tool shown inFIG. 12C.

FIG. 13A is a side view of an embodiment of an elastomeric access sheathhaving a rigid plastic internal collar to create a low friction surface.

FIG. 13B is a front end view of the access sheath shown in FIG. 13A.

FIG. 13C shows a rigid collar for installment in an access sheath, withthe rigid collar having radial slots to allow the rigid collar to flex.

FIG. 13D shows the rigid collar of FIG. 13C installed in an accesssheath.

FIG. 13E is a side view of the rigid collar shown in FIG. 13C.

FIG. 13F is a side view of an embodiment of an elastomeric access sheathhaving the rigid plastic internal collar shown in FIG. 13C.

FIG. 14 shows the access sheath with an external rim of elastomer tocreate an atraumatic tip.

FIG. 15 is a side view of the access sheath of FIGS. 3-9B with preferreddimensions and angles.

FIG. 16 is a bottom view of the sheath shown in FIG. 15.

FIG. 17 is a section view of the sheath shown in FIG. 15.

FIG. 18 is left end view of the sheath of FIG. 15.

FIG. 19 is a right end view of the sheath of FIG. 15.

FIG. 20 is an enlarged detail view of detail A shown in FIG. 18.

FIG. 21 is front, top and right side perspective view of the sheathshown in FIG. 15.

FIG. 22 is rear, bottom and right side perspective view of the sheathshown in FIG. 15.

FIG. 23 is an enlarged perspective view of a surface of a compositesurgical sheath made of a braided material with a sealing material inthe interstitial spaces of the braided material.

FIG. 24. is a graph of performance data of the sheath shown in FIG. 23.

FIG. 25 is a plan view of the sheath shown in FIG. 23, with a surgicaltool and a human nasal anatomy model.

FIG. 26. is a perspective view of the sheath shown in FIGS. 23 and 25,with the sheath now folded by a gloved human hand.

FIG. 27 is a perspective view of the folded sheath of FIG. 26 with thesurgical tool of FIG. 25 grasping the folded end of the sheath.

FIG. 28 is a perspective view of placement of the sheath of FIG. 27using the surgical tool.

FIG. 29 is a perspective view of the sheath in place.

DETAILED DESCRIPTION

FIG. 1 shows a braided tube 20 in its natural braided state. In FIG. 2the braid is shown on a cylindrical mandrel 22 to demonstrate itstubular shape and ability to expand. The braided tube 20 can be drawndown to a smaller diameter by stretching and pulling the monofilamentsinto a more longitudinal alignment. Conversely, the braided tube 20 canbe expanded to a larger diameter by compression and pushing thefilaments into a more radial directed alignment.

The braided tube 20, especially if made of plastic, can be placed arounda mandrel 22 that causes the braided tube 20 to expand to a specificdiameter or shape. The braided tube 20 can then be heat set in an oven.Upon cooling the braided tube 20 will be permanently formed into theshape of the mandrel 22. Heat setting mandrels can be made of hollow orsolid stainless steel, Delrin (acetal homopolymer resin). Mandrels 22may be made of Teflon (fluoropolymer), especially if intended to coatthe braided tube in a plastic/rubber/silicone dispersion. Heat settingcan be done at a variety of temperatures and time, depending on thebraided tube material and the heat capacity of the mandrel 22. A usefulheat set temperature for nylon or PET braids is 120° C. and 150° C. forhalf an hour, followed by cooling to room temperature in ambientconditions or a quench in water.

FIG. 2 shows braided tube 20 loaded over a Delrin® forming mandrel 22prior to heat setting. The mandrel 22 may be sized and shaped to productan access sheath having the shape and dimensions discussed in U.S. Pat.No. 8,986,201, incorporated herein by reference, and as shown in FIGS.15-22.

FIG. 3A shows a forming mandrel 22 in a geometry for manufacturing anaccess sheath 40. FIG. 3B shows a braided tube 20 placed over and aroundthe mandrel 22. After the braided tube 20 is loaded over the formingmandrel 22, the braided tube 20 may be conformed to the shape of themandrel 22 by a partial or complete wrapping of self-adhering siliconetape over the braided tube 20, or alternatively via a shaping blockpressed onto the braided tube 20 on the mandrel 22, with the shapingblock having an internal opening complimentary to the mandrel, but sizedto account for the thickness of the braided tube 20.

FIG. 4 shows the braided tube 20 after it has been heat formed, removedfrom the mandrel 22 and trimmed at both distal and proximal ends. Thisresults in a highly flexible, thin, and simple to manufacture accesssheath 40. This sheath 40 is permeable which allows natural mucuslubrication of the sinus to enter into the access sheath for additionallubricity. The braiding pattern may be modified to allow more or lesspermeability by changing the diameter of fibers or filaments of thebraid material. Flat monofilament or multi-filar fibers may be used toincrease the PIC (how tight the braiding is formed), and reduce theinterstitial spacing between fibers of the braided tube 20.

The braided tube 20 may be coated with a semipermeable or morepreferably an impermeable membrane. A less tacky coating or a harderurethane material, of durometer 50 A or harder, may be used. It can beapplied in thicknesses of 0.1 mm to 0.3 mm. Due to the thinness and theflexibility of the braided tube, even when coated the braided tube maystill remain flexible, foldable, and be able to elongate.

In an alternate embodiment a PET (Polyethylene Terephthalate) braidedtube can be used with a uniform coat of a silicone dispersion (NusilMED16-6606). Despite being silicone this combination provides a slicksurface relative to surgical tools. This can be attributed to themechanical nature of the structure. The braid surface provides anon-continuous, undulating surface where a full surface contact isreplaced by a series of discrete contact points. Discrete contact pointsreduce the surface area of contact and hence reduce the friction betweenaccess sheath 40 and the surgical tool.

A single layer braided tube coated in an impermeable silicone, such asNUSIL silicone dispersion 6061, was found to be a good coating as itapplies in a thin layer and despite being silicone (that has inherenttackiness) has little tack. The resulting friction as tested showed 50grams of friction. This is about the same friction as hydrophilic coateddevices when tested new. The lubricious nature of the material also doesnot degrade over time, unlike hydrophilic coatings.

Examples of lubricious coatings are: ceramic coatings. Slick-Sil coating(by Surface Solutions Group), Parylene coating, and hydrophiliccoatings. Similar coatings can provide better friction reduction but maynot feel as lubricious as mucous membrane.

Hydrophilic coating provide lubricity similar to mucous membranes,however they require wetting with water or saline to activate, and needperiodic or continuous re-wetting to stay slick. Hydrophilic coatingsalso wear away after multiple abrasions with surgical tools and may notwithstand the long procedure time of skull base neurosurgery. Examplesof lubricious additives are: barium sulfate, powdered Teflon(fluoropolymer) glass fillers, and ceramic fillers. These can reduce thesurface tack but also tend to provide a surgical tool feel that isdifferent from mucous membranes.

The elastomeric coating on the internal surface of the braided tube 20may be reduced. If the mandrel 22 is created from a semi flexible rubberor jacketed in rubber it results in a flexible surface. If the braidedtube 20 is loaded over this surface and stretched to tightly engage themandrel 22, the internal contact points of the braided tube embedslightly into the semi-flexible mandrel surface. This effectively masksthe internal surface of the braid. A coating step fully coats theexternal braided tube while leaving the highest contact points of theinternal braided tube uncoated and fully retaining the inherentlubricity of the hard plastic monofilament of the braided tube. A semiflexible surface may also be achieved by jacketing the mandrel inpolyolefin shrink tubing. When the braid/jacket mandrel are heated forshaping, the shrink tubing softens and the braided tube will slightlyembed. This similarly creates a braid/mandrel assembly that has apartially masked inner braid surface for a follow up coating step.

FIG. 5 shows a formed braided tube that has been coated in the siliconedispersion described above. The distal end may be made atraumatic forinsertion in the delicate anatomy of the nasal cavity, for example byusing a double layer 36 of the braided tube material, in contrast to thesingle layer 34 shown in FIG. 4. The double layer 36 may be provided byinverting the braided tube 20 to create a dual wall braided tube with anun-cut, rolled or rounded edge 32.

FIG. 6 shows a formed braided tube 20 having an inverted braid section30 to create the rounded edge 32. The rounded edge 32 can be dippedcompletely into a coating. This creates an impermeable surface in asimple way, although it may reduce flexibility or the ability to drawdown and fold since both braid layers are bonded together.

FIGS. 7A-7C show an alternative to the rounded edge design of FIG. 6,with the benefit of the rounded edge 32 has no coating on the innersurface, while the outer surface is coated, and does not bond the layerstogether preserving a thinner wall and flexibility.

Referring now to FIG. 7A, the right side of the braided tube 20 isformed on a mandrel 22 and then coated. The left side is not formed orcoated. Referring now to FIG. 7B, the uncoated braid (left side) isinverted and loaded through the shaped and coated right side portion.Referring now to FIG. 7C, the rounded edge 32 (formed via the invertingstep) and the coated external surface and uncoated internal surface areshown. For comparison, FIG. 8A shows an access sheath with a straightedge while FIG. 8B shows an access sheath 40 with a rounded edge 32.

As is apparent from the description of FIGS. 3-8B above, a method ofmaking a surgical access sheath may include placing a length of braidedtube material over a mandrel; conforming the braided tube material tothe shape of the mandrel; heating the braided tube material to heat setthe braided tube material; removing the braided tube material from themandrel; and cutting the heat set braided tube material to a desiredlength. The conforming step can be performed by at least partiallywrapping tape over the braided tube material, or placing a shaping blockhaving an internal opening complimentary to the mandrel, over thebraided tube material.

A monofilament material having round or flat fibers may be used as thebraided tube material. A sheet or strip of braid material may also beused in place of a tube, with the sheet or strip formed into a tubeduring the manufacturing process. For example, a strip of braid materialmay be wrapped around the mandrel and formed into a tube via the heatsetting. A coating may be applied to at least part of the heat setbraided tube.

Internal contact points of the braided tube material may optionally beembedded into the mandrel surface, and a coating applied onto at leastpart of the heat set braided material. One or both ends of the heat setbraided material may be folded or rolled to form an atraumatic end.

FIGS. 9A and 9B show a finished access sheath 40, and demonstrate itsability to conform to significant angulation of surgical tools 42 and44. The access sheath 40 can stretch as shown in FIG. 9B when surgicaltools are angulated and apply a spreading load on the access sheath 40.In typical endonasal skull base procedures, multiple surgical tools areused to stretch the naris in order to increase the angle formed by twosurgical tools creating a triangulation rather than bringing the distalends of the surgical tools together. The access sheath 40 can preferablystretch as much as or more than the tissue of the naris. The accesssheath 40 can accommodate the varied anatomy of the human nares andstretch and contract to accommodate surgical tool requirements.

The access sheath 40 may be compressed or folded for low profileplacement and high profile working position. In a simple case the accesssheath can be folded by hand and slid into the sinus manually. Loadingtools or kits may also be used.

FIG. 10A-10G show a system or kit 50 for low-profile insertion of theaccess sheath 40. FIG. 10A shows the access sheath 40 next to anelongated tubular loading tool 52. The loading tool 52 has a flaredproximal end 54 to aid in channeling the access sheath 40 into theelongated tubular body 62 of the loading tool 52. The loading tool 52has a slot 56 along one side to allow the access sheath 40 to beseparated from the loading tool after it is placed in the nose of thepatient. FIG. 10B-10F show the placement of the access sheath 40. Theaccess sheath 40 can be loaded via the loading tool 52 to 1) Compressand control the access sheath 40 into a compact volume; 2) provide astreamlined low profile shape for inserting the access sheath 40 intothe narrow space of the nasal opening and cavity; and/or 3) provide aconduit for deploying the access sheath 40.

The loading tool 52 has a flared proximal end 54 to allow the accesssheath 40 to be easily inserted into the loading tool 52 and compactedinto a small volume. A tubular body 62 is joined to the flared proximalend 54 of the loading tool 52. The tubular body 62, which may bestraight or have a slight taper towards the distal end, is designed tofit into the nasal opening. The slot 56 along the side of the loadingtool 52 provides a conduit for the access sheath 40 to be deployed andreleased.

The kit in FIGS. 10A-10G may be provided with an access sheath 40comprising a braid material, and a loading tool 52 having a conicalproximal end, and a tubular distal end, and the slot 56 extending alongone side of the loading tool, along the entire length of the loadingtool. The loading tool comprises a flexible material to allow the slotto be pushed open further, to better allow the sheath to moved out ofthe loading tool into the nose or other body cavity. The slot has awidth equal to 25% to 45% of a minimum diameter of the tubular distalend.

Turning to FIG. 11A, in an alternative access sheath kit, the accesssheath 40 may optionally be folded and slid into a tube 70. The tube 70may be a thin walled round or oval tube, optionally with an annularcollar 74 at the back or proximal end to provide a grasping surface. Thefolded or rolled access sheath 40 may be inserted into the distal orproximal end of the tube. The plunger 72 is inserted into the proximalend as shown in FIG. 11B. The tube 70 is then introduced into the nose.Advancing the plunger while holding the tube stationery pushes theaccess sheath 40 out of the distal end of the tube as shown in FIG. 11C.The tube and plunger may then be withdrawn by pulling back on the tube,leaving the access sheath 40 in place in the nose. The plunger 72 mayhave an enlarged head 76 having a diameter greater than the collar 74 orthe tube 70, to limit the extent of travel of the plunger into the tube.

As shown in FIGS. 11A-11C, the surgical kit has an access sheath 40 madeof a braided material, and a loading tool set including the tube 70 andthe plunger 72 slidable into the tube. The access sheath 40 is foldableor compressible to fit into the tube, and with the access sheathexpandable when ejected from the tube by the plunger. The tube may havean outside diameter of 5 to 20 mm and be transparent or translucent.

FIG. 12A to 12C show another kit using a folding instrument 80 to fold,introduce and deploy the access sheath 40. The folding instrument 80 isa scissor-like device having a bottom jaw 82 having an elongated groovedchannel 84. The top jaw 86 is an elongated rod or beam pivotallyattached to the bottom jaw 82, with a handle at the back end of eachjaw.

In use the instrument 80 is opened, as shown in FIG. 12A and the accesssheath 40 is placed between the open jaws 82 and 86, or over one of thejaws. Squeezing the handles towards each other pivots the jaws towards aclosed position shown in FIG. 12B, with the access sheath folded betweenthe jaws. The jaws are then inserted into the nasal cavity and openedslightly to release the access sheath. The instrument 80 is removedwhile the access sheath 40 is left in place. The instrument 80 can bere-inserted into the internal channel 45 of the access sheath 40 andthen manipulated open and closed to help open and expand the accesssheath as needed.

The designs of FIGS. 12A-12C if provided as a surgical kit, includes theaccess sheath 40 made of a braid material, and the scissor-like loadingtool having the first jaw pivotally attached to the second jaw, with thefirst jaw having a channel and the second jaw movable at least partiallyinto the channel when the scissor-like loading tool is in a closedposition, to fold the access sheath.

Referring to FIGS. 13A and 13B, a conical collar insert 90 may be placedin the angle section 154 and flare section 156 of the access sheath 40,shown in FIGS. 15-22. The insert 90 may be made from a hard plastic ormetal so that it is inherently lubricious relative to metal or plasticsurgical tools 44. The insert 90 provides a lubricious bearing surfaceat the angle and flare sections of the access sheath 40, where surgicaltools 44 extensively contact with the access sheath 40.

FIGS. 13B to 13E show an alternative conical collar insert 100 which isa rigid collar having radial slots 102 to allow it to flex into a moreopen state in response to forces exerted by surgical tools 44. Thisallows the surgical tools 44 to be more easily moved into larger acuteangles relative to each other. The collar inserts 90 and 100 may eachhave a flared section 110 joined to a tubular section 112 havingstraight or parallel walls. Alternatively the tubular section 112 mayhave a reverse flare wherein it tapers outwardly towards the distal end.As shown in FIGS. 13A and 13D, the flared section 110 has a shape anddimensions to allow it to fit and be attached into the flare section 156of the access sheath 40. The tubular section 112 is similarly configuredto fit into the angle section 154 of the access sheath 40. The inserts90 and 100 may be attached to the access sheath 40 via adhesive,plastics welding, shrink fit, molded into place, snap fit, etc.

FIG. 14 shows an access sheath 40 with a distal end 120 of an elastomerto create an atraumatic tip 122. The elastomer can be an internal andexternal rim. Preferably the elastomer is only on the external surfaceso as not to create an internal surface of elastomer. This provides anatraumatic tip 122 but does not create an internal elastomeric surfacethat could result in a friction inducing surface at the distal end ofthe internal channel 45 of the access sheath 40. The elastomer may beprovided a cut edge of a single layer of braided tube material, or overthe rounded edge 32 of a access sheath 40 having two layers of braidedtube material at the edge.

The elastomer may extend proximally 1-50 mm on the external surface ofthe access sheath 40. The external extended elastomeric surface 124provides a user selectable section that may be cut to a desired length.When cut, a portion of the external extended elastomeric surface 124remains on the access sheath 40 and provides an atraumatic distal rim.An external rim of elastomer may similarly be used on the proximal endof the access sheath. This provides a section at the proximal end thatmaintains the integrity of the braided tube and avoid fraying. Theexternal rim of elastomer on the proximal rim, if used, may only be onthe external surface so as not to create friction on surgical toolspassing through the internal channel 45.

FIGS. 15-22 show dimensions and angles which may be used for the accesssheath 40. The mandrel 22 may be sized and shaped to form an accesssheath as shown in these Figures. In this example, the access sheath 40has a body section 152, and angle section 154 and a flare or conicalsection 156. The sheath 40 may be formed of braid material as a onepiece unit with the body section 152, the angle section 154 and theflare section 156 integrally joined together. As shown in FIG. 20, thesheath 40 may have a thin flexible wall 158 having a thickness TT whichallows the sheath to conform to the body orifice, or the inner wall ofthe patient's nostrils in the case of nasal access. The flare section156 may be provided as a conical ring forming an angle DD of 120-160 or130-150 degrees with the top wall of the angle section. The sheath 40may have a single through internal channel 45 extending from a distalopening 162 to a proximal opening 165. As shown in FIGS. 18, 19 and 22,the openings 162 and 165, and the cross section of the body section 152,may be generally in the shape of an oval or an ellipse.

Referring to FIGS. 15 and 17, the distal opening 162 may lie in a planeforming an angle forming an angle BB with the bottom of the sheath 40,with BB ranging from 95 to 125 or 100 to 115 degrees. As best shown inFIG. 17, the angle section 154 may be described as joined to the bodysection 152 at a vertical line 151. The upper and lower walls of thesheath extend distally away from the vertical line 151 towards thedistal opening 162 at acute angles to the vertical line 151, which maythe same or different angles. As shown in FIG. 15, the included angle CCbetween the top surface of the angle section 154 and the lower wall ofthe body section may range from 25 to 40 or 30 to 35 degrees. The anglePP in FIG. 15 relating to the diverging angle of the top and bottomsurfaces of the body section is typically 10-20 or 12-16 degrees.Dimension KK may be 8-16 or 10-14 mm, with dimensions MM and SS bothgenerally about 65-85 or 70-80 mm.

As shown in FIGS. 15-17, a surgical sheath 40 includes a conicalsection; an angle section joined to the conical section, with theconical section having a central axis AF not parallel to a central axisAN of the angle section; a body section joined to the angle section,with the body section having a length at least twice the length of theangle section; and the conical section, the angle section and the bodysection comprising a braid material. The sheath 40 may further includean insert 90, 100 inside of the conical section, with the insert made ofa non-braid material. An elastomer coating may be provided on at leastpart of an external surface of the sheath. The sheath may have a rollededge at its distal end.

Turning to FIGS. 15-16 and 20-22, one or more ridges 64 may be providedon an outer surface of the body section 152. The ridges may optionallybe provided as rings extending continuously around the outside surfaceof the body section. The dimensions and angles shown in the drawings ofall embodiments may typically be varied by 10, 20 or 30% depending onvarious design parameters.

The angle section 154 may allow the proximal end of the sheath 40 to bemore easily stretched and/or deflected. This allows for more versatilemovement of surgical tools extending through the sheath during surgery.As shown in FIGS. 15 and 17 the angle section 154 forms an irregularquadrilateral shape in cross section. In FIG. 17 the angle section 154may be defined by line F4 along with segments or lines F1, F2 and F3,with F4 and F2 forming a first acute angle and with F1 and F3 forming asecond acute angle. Each of the sides or segments F4, F1, F2 and F3forming the angle section 154 may also have different lengths. F3 may besubstantially perpendicular to F2. The angle section 154 mayalternatively be described via a centerline AN perpendicular to andbisecting segment or line F4 and intersecting a centerline AF of theflare section 156 at an angle AB of 5-30 or 10-20 degrees.

One method for placing a surgical access sheath includes loading asurgical access sheath into a loading tool, with the surgical accesssheath comprising a braid material, and with the loading tool having aconical proximal end, and a tubular distal end, and a slot extendingfrom the conical proximal end to the tubular distal end; inserting theloading tool into a body orifice; inserting a surgical tool into aninternal channel of the surgical access sheath; moving the surgical toolto move the surgical access sheath out of the loading tool through theslot; and withdrawing the loading tool from the body orifice.

Another method for placing a surgical access sheath includes placing asurgical access sheath into a low profile delivery position, with thesurgical access sheath comprising a braid material; loading the surgicalaccess sheath into a tube; inserting the loading tool into a bodyorifice; moving a plunger into the tube to eject the surgical accesssheath out of the tube and into the body orifice; and withdrawing thetube from the body orifice.

Another method for placing a surgical access sheath includes providing ascissor-like loading tool having a first jaw pivotally attached to asecond jaw, with the first jaw having a channel and the second jawmovable at least partially into the channel when the scissor-likeloading tool is in a closed position; providing a surgical access sheathcomprising a braid material, with the access sheath having an internalchannel; placing the access sheath around one of the first jaw and thesecond jaw, while the jaws are in an open position; moving the jaws intothe closed position, to fold and grasp the surgical access sheath;inserting the jaws into a body orifice; opening the jaws to release thesurgical access sheath; and removing the jaws from the body orifice.

A surgical kit includes an access sheath comprising a braid material;and a loading tool having a conical proximal end, and a tubular distalend, and a slot extending from the conical proximal end to the tubulardistal end. The loading tool may comprise a flexible material. Typicallythe slot extends along an entire length of the loading tool. The slotmay have a width equal to 25% to 45% of a minimum diameter of thetubular distal end. The access sheath may have a conical section, anangle section joined to the conical section, with the conical sectionhaving a central axis AF not parallel to a central axis AN of the anglesection, a body section joined to the angle section, with the bodysection having a length at least twice the length of the angle section.Alternatively, the loading tool may have a tube and a plunger slidableinto the tube, with the access sheath foldable or compressible to fitinto the tube, and with the access sheath expandable when ejected fromthe tube by the plunger. If used, the tube may have an outside diameterof 5 to 20 mm, and it may be transparent or translucent. A scissor-likeloading tool may also be used, with the scissor-like loading tool havinga first jaw pivotally attached to a second jaw, with the first jawhaving a channel and the second jaw movable at least partially into thechannel when the scissor-like loading tool is in a closed position, tofold the access sheath.

Surgical instruments must be able to pass across the surface of thebraided structure with minimal friction and without catching on thebraid or the interstitial space between the braid elements. For thestructure to be useful it must be comprised of a tight, dense, braidpattern with minimal interstitial space.

FIG. 23 is a magnified image of a braided access sheath. Interstitialspaces are formed between the adjacent and intersecting fibers formingthe braid material. In FIG. 23, the interstitial spaces are generallysquare. Depending on the overall curvature of the sheath, and on thedirections applied forces in compression or tension, the interstitialspaces may have other quadrilateral shapes, including isoscelestrapezoid, rhombus or diamond, parallelogram and kite (i.e., rhombuswith two adjoining longer sides and two adjoining shorter sides).

The shapes of the interstitial spaces may change during use as thebraided material stretches or compresses. As used here, an interstitialspace is defined as an equilateral quadrilateral with a dimensionrepresented by the length of one side, in the as manufactured shapewithout any forces acting on the sheath.

The braid material of the access sheath may have interstitial spaceswith a dimension of between 0.50 mm (0.020 in.) to 0.75 mm (0.030 in.),or 0.25 mm (0.010 in.) to 1.50 mm (0.060 in.)

Minimizing the interstitial space is significant because a smallinterstitial space between the braid elements creates a weave which isdifficult for tools to snag on or poke through. A small interstitialspace between the braid fibers also allows a coating of a filling orwater proofing material, such as silicone (polysiloxane) to span theinterstitial space. The larger the interstitial spaces, the moredifficult it is for the coating to maintain coverage across the spaces.Spaces not fully covered, or filled in, with a coating create voids orpinholes which may tend to cause the tip of a tool to catch or snag inthe braid material. Materials such as silicone may be used for thefilling or water proofing material, including polymers, natural andsynthetic rubbers, and elastomers generally. These may be applied to thebraided material by dipping, spraying, rolling, etc. The fillingmaterial fills in the interstitial spaces, and may or may not also forma layer thickness above the braided material, on the inside and/or theoutside surface of the sheath.

If the interstitial space is too small, it may create issues inmanufacture and use of the sheath, as the braid sheath material ineffect approaches becoming a solid material. Additionally, someinterstitial space allows a coating to access and encapsulate the braidfibers. Without interstitial space the coating would only be able toform a surface film. A surface film may be prone to delamination withcompression, stretch, or tool passage and create a higher frictioncoefficient. Additionally, there is a frictional benefit from having asurface that in not continuous. The discontinuous surface formed by thefibers of the mesh material reduce the surface area in contact withtools and directly reduces static and dynamic friction acting on thetools. For these reasons it is preferred to maintain an interstitialspace of at least 0.25 mm (0.010 in).

The braided material used to form the sheath advantageously has one ormore of the following properties:

A braided tube that can expand to approximately 4 times its initial lowprofile diameter. This means when braided, it is made in its lowestprofile diameter but with the application of compression (by pushing theends towards each other), the diameter of the braided tube can expand to4 times the diameter.

The braided tube has an outside diameter of approximately 10 mm (⅜ in.)and can expand to approximately 40 mm (1½ in.).

The braided tube has as a full load braid pattern, meaning that anyindividual strand passes over two strands and then under two strands andthen back over two strands, with this path continuous throughout thebraided tube and for each individual fiber.

The braided tube is made from 0.25 mm (0.010 in.) diameter, round PET(polyethylene terephthalate) monofilament.

The braided tube is made from 96 individual fibers.

The braided tube, when placed over a 25 mm diameter (1 in.) rod hasapproximately one pic per millimeter or 24-26 pics per one inch, i.e.,the count of crossing pairs of fibers along a straight longitudinal lineon the braid surface per unit length. It is a measure of the braiddensity at that particular diameter.

An access sheath that has a high coefficient of friction may impede freemovement of surgical instruments. The sheath should also advantageouslymaintain lubricity for the entire duration of the surgical procedure,which may be several hours, with surgical instruments extended andwithdrawn through the sheath multiple times. Lubricity refers to thefriction occurring when an object (such as surgical tool) slide acrossthe material of the sheath, i.e., how slippery the material is.

An access sheath without inherent lubricity requires use of an externalsurgical lubricant, or using water or saline solution as a lubricant.However, this requires repeated or continual application of the surgicallubricant or flushing of water or saline, to maintain consistentlubricity. Hence, using an external lubricant introduces an additionalstep to the surgical procedure, which slows the surgical procedure,while also potentially obscuring visualization of the surgical field.

A hydrophilic coating may optionally be applied to the surface of theaccess sheath. However, this requires wetting the device to activate thecoating. Hydrophilic coatings may also decrease in lubricity over thecourse of a long procedure with large numbers of instrument passes.

The present sheath may be provided as a composite structure of a braidedmaterial and water proofing material. The water proofing material may besilicone. The present composite structure sheath can provide longlasting lubricity, in contrast a simple molded rubber access sheath. Thepresent braided material composite sheath does not require theapplication of lubricants and maintains its performance throughout thelength of the procedure.

The silicone (or equivalent material) may be applied to the braidedmaterial by dip coating. The silicone is provided to make the braidedmaterial water proof, i.e., in the sense of preventing water frompassing through the braided material. The silicone is not needed toprovide lubricity because the braided material itself provideslubricity. The silicone fills in the interstitial spaces between thefibers of the braided material. Advantageously, the silicone has amaximum layer thickness of 0.13 mm (0.0005 inches). Maximum layerthickness refers to the thickness of the silicone, not including thethickness of the braided material. Stated differently, advantageouslythe thickness of the silicone does not project above or below the fibersby more than 0.13 mm.

For example, if the braided material is made of fibers having a 0.25 mm(0.01 inch) diameter, the total thickness of the silicone isadvantageously 0.25 mm to 0.51 mm. Excessive thickness of silicone (orequivalent material) decreases lubricity.

The composite sheath achieves its performance because it has anon-continuous contact surface. Rather, the surface is a series ofdistinct contact points due to the undulating surface texture created bythe spaced apart fibers.

Instead of instruments contacting a flat surface of an elastomer,instruments have minimal contact area with the bumps formed by thecrossing of round monofilament fibers. The sheath allows a highdurometer and less tacky material (such as PET monofilaments) to stillhave the foldability, stretchability, and conformability, that wouldotherwise require an elastomer with a lubricant as described above.

FIG. 24 shows functional test data of a hydrophilic coated elastomericsheath compared to the present inherently lubricious composite sheath.The test data was generated using a stainless steel rod representing aninstrument applied with a normal load of 4.4 Newtons (1 pound force)while the instrument was passed forward and backward. FIG. 24 representsroughly 200 instrument passes representing a multi-hour procedure.

A method of insertion, placement and deployment of a braided accesssheath 166 is described below. This method uses a pulling force ratherthan a pushing force as the unique braided structure of the sheath willtend to resist pushing forces as the diameter of the sheath increaseswith pushing forces. FIG. 25 shows a nasal anatomy model with a braidedaccess sheath 166 and a deployment tool. The braided access sheath 166is shaped to generally match to the natural passageway of the sinuscavity. The top or superior side 172 has a hump 176 that follows thenatural opening of the sinus cavity and allows the sheath to open and toprovide greater working space. Referring momentarily back to FIG. 17 forexample, the hump 176 is formed via the intersection of surfaces 152 and154. Similar to the sheath of FIG. 17, the sheath 166 is also bevertically non-symmetrical about its centerline AN, i.e., the shape,orientation, and or dimensions of the top surface of the sheath are notthe same as, and not mirror images of, the bottom surface of the sheath.Thus, for improved deployment, the sheath 166 is advantageously aligned(relative to sinus cavity) in a superior/inferior direction and thenfolded as shown in FIG. 26.

FIG. 26 shows the braided access sheath 166 with the top of the sheath(superior side) being folded to the bottom (inferior side) to preparefor deployment. By folding the superior side 172 of the sheath to theinferior side 174 or vice versa, the sheath diameter is now capable ofbeing inserted the naris of a patient.

Once folded, the sheath 166 can be grasped and held in position with anystandard medical tool 168 such as a pituitary forceps, a curvedhemostat, a standard hemostat, or any medical instrument that can holdthe folded sheath as shown in FIG. 27. Typically, the tool is used tograsp the folded distal end of the access sheath 166. Using the tool168, the sheath is then pulled into the sinus cavity either under thedirect visualization of a scope or without as shown in FIG. 28. Thesheath can be placed to user's preferred distal position. The sheath 166may be adjusted distally or proximally until it is in the properoperating position as shown in FIG. 29. In FIG. 29, the sheath isdeployed and expanded, with the sheath conforming to the nasal cavityand naris.

An access sheath may protect the anatomy from multiple passes ofinstruments, provide a hood to keep the scope clean, and minimize therun-in of blood to the operating site.

The run-in of blood into the operating site comes primarily from theanatomical dissection performed in the proximal sinus cavity prior tothe placement of the access sheath. This may include the creation of anasal flap, removal of turbinates or bleeding from instrument passage.Hence, the ability of an access sheath to stop or minimize blood run-inis advantageous.

Relative to blood run-in, an access sheath having a thin wall isprovided, so that it can be folded into a minimum compact profile duringplacement but then have sufficient memory, expansion range, andexpansion strength to expand against the anatomy when deployed.Expanding outwardly or splinting against the sinus cavity maximizes theopen visual surgical field allowing better exposure for the surgery aswell as providing a tamponading force against any bleeding in theproximal sinus cavity.

The access sheath may be made of a composite coated braid structurehaving a wall thickness of 0.38 mm to 0.88 mm (0.015 to 0.035 in.), or0.52 to 0.72 mm (0.020 to 0.029 in.).

Correspondingly the access sheath has an expansion strength of 100-200or 170 to 200 grams force as measured with a 3 mm (0.38 in.) rodpressing into the sheath at the longitudinal and vertical center of thesheath for 6 mm (0.25 in.) displacement. Expansion strength refers tothe amount of outward force the sheath can exert on surrounding tissue.For sheaths having a generally oval cross section, for example as shownin FIG. 13B, 17, 21 or 29, expansion strength in the vertical direction(across the longer axis of the passageway through the sheath, in thedirection of line F4 in FIG. 17), will be greater than the expansionstrength in the lateral direction (laterally inwardly across the shorteraxis of the passageway, in the direction of dimension WW in FIG. 19).Expansion strength as used here refers to minimum expansion strength,which will typically be the expansion strength in the lateral direction.

A metric on the splinting efficiency of the access sheath is expansionstrength per unit of wall thickness, expressed as:

expansion strength/wall thickness=T ratio in gm/mm.

For example, a sheath having an expansion strength of 190 gm and a 0.62mm (0.025 in.) wall thickness would have a T ratio of 190 gm/0.62 mm=306gm/mm]. Generally sheaths having a T ratio of about 200 to 400 may beused.

The sheath shown in FIGS. 23-29 is generally made of a combination of asingle layered braid and an elastomeric coating which fills theinterstitial spaces between the braided elements. This structure createsan embodiment with sufficient expansion strength to tamponade, splintopen, and interlock with the anatomy. Either component of the compositestructure can be adjusted to adjust the expansion strength. Themonofilament size of the braid can be increased or decreased to increaseor decrease the expansion strength. Similarly the thickness or durometerof the coating can be adjusted to increase or decrease the expansionstrength. The preferred embodiment uses PET monofilaments of a diameterof 0.25 mm (0.010 [in.) and a coating thickness of less than 0.13 mm(0.005 in.) to produce specifications in a composite structure with wallthickness minimized and sufficient expansion strength.

An alternative embodiment is made of a single layer of braid material,such that the wall thickness of the sheath is equal to the diameter ofthe braid fibers plus the thickness of the layer or coating (e.g.,silicone) on the inside and on the outside of the braid fibers. However,sheaths may optionally be made with two or more layers of braidmaterial, over entire or substantially the entire sheath, or overselected portions of the sheath. For example, a central area of thesheath may have a narrow reinforcement band with a second layer of braidmaterial, to locally increase expansion strength. Similarly, areinforcement band of a second layer of material may be provided at thedistal and/or proximal end of the sheath.

Along with splinting the anatomy to provide improved surgical access,the expansion strength of the access sheath provides a tamponade againstthe sinus nasal cavity anatomy wall. This helps reduce seeping of bloodflow that could result from minor abrasions during placement of theaccess sheath and/or existing bleeding injuries. Tamponade of blood flowthen results in a cleaner surgical field as migrating blood flow alongthe surface and to the distal end of the access sheath is minimized.Post surgery the sheath may be left in place to continue to tamponading,and as an aid to healing and recovery while providing an open breathingpassageway to better allow the patient to breath more freely.

Additionally, the expansion strength and associated anatomical fill,helps to maintain the access sheath in position. If the access sheathconforms to and slightly impinges on the anatomy, it then forms aninterlocking shape with the anatomy which tends to resist migration ofthe sheath.

Thus, a novel surgical sheath and methods have been shown and described.Each of the features described in association with a specific embodimentmay of course also be used in other embodiments described. Variouschanges and substitutions may of course be made without departing fromthe spirit and scope of the invention. The invention, therefore, shouldnot be limited except by the following claims and their equivalents.

1. A surgical sheath comprising: an elongated hollow body comprising abraided material having interstitial spaces with a dimension of 0.25 mmto 1.50 mm and the interstitial spaces filled with a filling material.2. The sheath of claim 1 with the interstitial spaces having a dimensionof between 0.50 mm to 0.75 mm.
 3. The sheath of claim 2 with the fillingmaterial comprising silicone.
 4. The sheath of claim 1 with the fillingmaterial having a maximum layer thickness of 0.13 mm.
 5. The sheath ofclaim 1 with the braided material comprising a braided tube that canexpand from a low-profile configuration to an expanded configurationsubstantially equal to at least four times the low-profileconfiguration.
 6. The sheath of claim 5 having a maximum diameter ofapproximately 8 to 12 mm when in the low-profile configuration.
 7. Thesheath of claim 1 with the braided material comprising a braided tubemade from round monofilament fibers having a diameter of approximately0.2 to 0.3 mm.
 8. The sheath of claim 7 with the braided tube made ofapproximately 76 to 116 fibers.
 9. The sheath of claim 7 with the fiberscomprising PET (polyethylene terephthalate).
 10. The sheath of claim 1with the elongated hollow body including a conical section; an anglesection joined to the conical section, with the conical section having acentral axis AF not parallel to a central axis AN of the angle section;and a body section joined to the angle section, with the body sectionhaving a length at least twice the length of the angle section.
 11. Thesheath of claim 1 having a lateral expansion strength of 100-200 grams.12. The sheath of claim 1 having a lateral expansion strength to wallthickness ratio of 200 to
 400. 13. A method of using a surgical accesssheath, comprising: creating a fold in distal end of the sheath;grasping the fold with a surgical tool; using the surgical tool to pullthe sheath into a nasal cavity of a patient, with a proximal end of thesheath remaining outside of the nose of the patient; unfolding thesheath to allow the sheath to conform to the nasal cavity; and removingthe surgical tool.
 14. The method of claim 13 wherein the sheath isvertically non-symmetrical, further including aligning a top surface ofthe sheath with the nasal sinus cavity before pulling the sheath intothe nasal cavity.